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Friday, September 8, 2017

Asteroid 2017 RS - an extinct comet?

Asteroid 2017 RS was first observed at Pan-STARRS 1, Haleakala on 2017-09-01. 
It is classified as a Mars-crosser.
Its orbit is still very uncertain (condition code 9).
It would be nice to have more data because this asteroid may be an extinct comet.

Orbital data

(2017 RS)

Classification: Outer Main-belt Asteroid          SPK-ID: 3781340
Ephemeris | Orbit Diagram | Orbital Elements | Physical Parameters ]

[ show orbit diagram ]

Orbital Elements at Epoch 2457998.5 (2017-Sep-02.0) TDB
Reference: JPL 1 (heliocentric ecliptic J2000)
 Element Value Uncertainty (1-sigma)   Units 
e .6145637063005263 0.020702
a 4.14837857496493 0.18924 au
q 1.598935662796787 0.016606 au
i 16.490996995339 0.23653 deg
node 221.6460003522266 0.96443 deg
peri 165.4311035552846 2.8664 deg
M 351.0338219139737 0.34606 deg
tp 2458075.363624646766
2.4617 JED
period 3086.142680565361
n .1166504718874665 0.0079819 deg/d
Q 6.697821487133073 0.30553 au
Orbit Determination Parameters
   # obs. used (total)      18  
   data-arc span      5 days  
   first obs. used      2017-09-01  
   last obs. used      2017-09-06  
   planetary ephem.      DE431  
   SB-pert. ephem.      SB431-N16  
   condition code      9  
   fit RMS      .20988  
   data source      ORB  
   producer      Otto Matic  
   solution date      2017-Sep-06 18:12:03  

Additional Information
 Earth MOID = .609695 au 
 Jupiter MOID = .352027 au 
 T_jup = 2.605 

Simulation in the past 
I used Mercury6 simulator by John Chambers to check what might have happened in the last 10^8 days (about 273000 years).
The arbitrary threshold for the ejection distance is 100 AU.

           Integration parameters

   Algorithm: Bulirsch-Stoer (conservative systems)

   Integration start epoch:         2458000.5000000 days
   Integration stop  epoch:      -100000000.0000000
   Output interval:                     100.000
   Output precision:                 medium

   Initial timestep:                0.050 days
   Accuracy parameter:              1.0000E-12
   Central mass:                    1.0000E+00 solar masses
   J_2:                              0.0000E+00
   J_4:                              0.0000E+00
   J_6:                              0.0000E+00
   Ejection distance:               1.0000E+02 AU
   Radius of central body:          5.0000E-03 AU

I generated 100 clones with a little R script.
Every orbital parmeter has an average similar to the correspondent nominal one.
Every orbital parameter has a standard deviation equal to the uncertainty shown above.

Result of the simulation for the nominal orbit
These graphs were made using the R ggplot package.

Result of the simulation with 100 clones
After the simulation, I got 78 out of 100 clones that arrived from the outskirt of the solar system.
The actual arrival date range is extremely high: the most recent date was about 1565 AD.

The arrival date distribution is like this (time here is expressed in years):

Kind Regards,
Alessandro Odasso

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